Some computer software applications are organized according to what is referred to as a “single volume architecture,” meaning that they store data in a single data file that resides on a single volume. This “volume” may be a physical volume, such as a disk drive, or it may be a virtual volume, such as a RAID set. The Exchange® e-mail program provided by Microsoft Corporation of Redmond, Wash. is an example of such a single-volume-architecture application.
In some cases, the single volume architecture of a particular software application can be problematic, because the size of the data file the application needs to store on a single volume exceeds the capacity of the volume. For example, implementations of Microsoft's Exchange® e-mail program in large organizations having many e-mail users can require a single-volume storage capacity exceeding 100 GB, which is greater than many conventional volumes, physical or virtual, can provide. Although it is possible to solve this problem by changing a single-volume-architecture application into a multi-volume-architecture application so that it saves data in multiple files spread across multiple volumes, such efforts can be prohibitively time-consuming and expensive.
Accordingly, there is a need in the art for a very large virtual storage volume having the storage capacity necessary to meet the needs of a single-volume-architecture software application, such as Microsoft's Exchange® e-mail program. Preferably, such a storage volume should have built-in disaster tolerance capabilities through the use of remote mirroring or other techniques in order to ensure the integrity of its stored data. In addition, such a storage volume should preferably have cloning capabilities so that data backup can occur off-line without interrupting read/write access to the data.